Regulation of the expression of three housekeeping genes encoding subunits of the Neurospora crassa vacuolar ATPase

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Abstract
The vacuolar ATPase is a complex enzyme and is encoded by at least nine genes, which appear to be scattered throughout the genome. We have examined the vma-1 vma-2, and vma-3 genes, which encode subunits present in multiple copies within the Neurospora crassa vacuolar ATPase. We wished to see if the expression of these genes is coordinately regulated and if these genes contain similar promoter elements. A region was sequenced of approximately 1 kb located upstream of the protein coding region for each gene. Several sequence elements were found in similar positions in each of the three genes. Each of the genes had several strong transcription initiation sites, clustered within 13–60 by and located 112–193 by upstream of the translation start site. The size and abundance of the RNA transcripts was also determined: the amount of RNA transcribed from each gene was roughly proportional to the numbers of each subunit present in the enzyme. A series of plasmids was constructed containing parts of the putative promoter region fused to β-galactosidase. Analysis of these plasmids indicated that the essential region of the vma promoters lies within 370 by of the protein coding region. Overall, the vma genes appear to have similar characteristics to “housekeeping” genes described in other organisms.